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PNWS AWWA 2008 Annual Conference Vancouver, Washington

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2. Contaminants of Emerging Concern in Water and Wastewater Treatment Nature of CECs
Removal mechanisms of CECs
Removal efficiencies of CECs during treatment
Do membrane bioreactors provide enhanced removal of CECs?
Other advanced treatment for higher levels of CEC removal

3. Recent AP article “Mary Buzby -- director of environmental technology for drug maker Merck & Co. Inc.: "There's no doubt about it, pharmaceuticals are being detected in the environment and there is genuine concern that these compounds….could be causing impacts to human health or to aquatic organisms.“
Recent laboratory research has found that small amounts of medication have affected human embryonic kidney cells, human blood cells and human breast cancer cells. The cancer cells proliferated too quickly; the kidney cells grew too slowly; and the blood cells showed biological activity associated with inflammation.
Some scientists stress … that the documented health problems in wildlife are disconcerting.

6. Surfactants Main surfactants of interest for ED are the alkylphenols (APs) and their ethoxylates (APEOs) – particularly the nonylphenol (NP) compounds
Alkyl Phenol Ethoxylates (APEO) widely used in industries as well as commercial and household functions
Detergents, lubrication, defoamers, emulsifiers, paints, pesticides
Cleaners for machinery, metal working, textiles, and personal products
Nonylphenol ethoxylate is the most common
APEOs tend to be degraded to more potent endocrine disrupting compounds during wastewater treatment
The ethoxylates can be degraded to produce NP which is more persistent and toxic than the ethoxylates
Highest freshwater concentrations of NP observed near WWTPs, pulp mills, and regions of heavy industry

7. Pesticides Largest group of EDCs
DDT, dieldrin, 2,4-D, tributyltin, atrazine, metolachlor, cyanazine, alachlor
All herbicides, fungicides, pesticides
Atrazine one of the most difficult to remove

17. Coagulation or Chemical Precipitation Most compounds of concern are relatively polar (Kow values < 3)
Neither alum or iron coagulation or lime softening effective for atrazine or antibiotic removals
Coagulation ineffective with several pharmaceuticals and with several pesticides
Some pesticides (PAHs pyrene, fluoranthene and anthracene) removed ~50% by coagulation
Coagulation only expected to remove hydrophobic compounds associated with particulate or colloidal material
EDCs and PPCPs not associated with colloidal or particulate material very poorly removed (<10%)

18. Adsorption Activated carbon (AC) effective for many different pesticides, PPCPs and EDCs
Hydrophobic interactions dominant mechanism (weak ion exchange interactions also contribute to adsorption)
AC can remove neutral organic compounds with hydrophobic compounds (logKow>2)
NOM in water competes for adsorption sites and decreases AC effectiveness for micropollutants
PAC can be effective; GAC probably more efficient
PAC could be good emergency measure at WTPs, particularly during low streamflow, and with upstream wastewater discharges

19. Membrane Filtration Most organic EDCs and PPCPs are 150 to 500 daltons
Most can be removed in RO and tight NF membranes
Microfiltration and ultrafiltration will only remove those EDCs and PPCPs associated with colloidal and particulate matter
Polar and charged compounds that interact with membrane surfaces will be better removed
Hydrophobicity also affects removals. Removals by RO and NF membranes correlates with logKow